The present invention relates to electronic network systems, and more specifically to a loop network hub designed such that loop initializations are detected and counted.
Electronic data systems are often interconnected using network communication systems. Approaches that have been developed for computer network architectures include area-wide networks and channels. Traditional networks (e.g., LAN""s and WAN""s) may offer flexibility and relatively large distance capabilities. Channels, such as the Enterprise System Connection (ESCON) and the Small Computer System Interface (SCSI), have been developed for high performance and reliability. Channels often use dedicated short-distance connections between computers or between computers and peripherals.
Features of both channels and networks have been incorporated into the Fiber Channel standard. Fiber Channel systems combine the speed and reliability of channels with the flexibility and connectivity of networks. Fiber Channel products often run at high data rates, such as 266 Mbps or 1062 Mbps. These speeds are sufficient to handle quite demanding applications, such as uncompressed, full motion, high-quality video.
There are at least three ways to deploy a Fiber Channel network, which include simple point-to-point connections, arbitrated loops, and switched fabrics. The simplest topology is the point-to-point configuration, which simply connects any two Fiber Channel systems directly. Arbitrated loops are Fiber Channel ring connections that provide shared access to bandwidth via arbitration. Switched Fiber Channel networks, called xe2x80x9cfabricsxe2x80x9d, are a form of cross-point switching.
Conventional Fiber Channel Arbitrated Loop (FC-AL) protocols provide for loop functionality in the interconnection of devices or loop segments through node ports. However, direct interconnection of node ports may be problematic since a failure at one node port in a loop may cause failure of the entire loop. This difficulty may be overcome in conventional Fiber Channel technology through the use of hubs. Hubs may include a number of hub ports interconnected in a loop topology. Node ports are connected to hub ports, forming a star topology with the hub at the center. Hub ports which are not connected to node ports or which are connected to failed node ports are bypassed. Therefore, the loop may be maintained despite removal or failure of node ports.
The inventors recognized that detecting and counting origination of loop initializations in a Fiber Channel Arbitrated Loop topology is desirable.
The present disclosure includes a hub port in a Fiber Channel loop. The hub port includes a hub data source, a loop initialization data detect circuit, and a loop initialization counter. The hub data source supplies data to the hub port from the Fiber Channel loop. The loop initialization data detect circuit is configured to detect valid loop initialization sequences from an attached node port and the hub data source. The loop initialization counter is configured to increment a count value of the valid loop initialization sequence from the attached node port if the loop initialization sequence from the node port does not match the valid loop initialization sequence from the hub data source. This state indicates that the loop initialization sequence is initiated by the attached node port.
The present disclosure also includes a method for detecting and counting loop initializations in a loop network. The method includes detecting a first valid loop initialization sequence received from a node port, and a second valid loop initialization sequence received from a hub data source. The detection of the two sequences from the node port and the hub data source occurs substantially simultaneously. The method also includes comparing the first and second valid loop initialization sequences. Finally, a count value is incremented if the first and second valid loop initialization sequences differ.